Chapter 41 Animal Nutrition

Nutritionally Adequate Diet Fuel Fuel Biosynthesis raw materials Biosynthesis raw materials Essential nutrients Essential nutrients

Fueling Life Balance caloric intake and output Balance caloric intake and output Excess stored as glycogen and fat Excess stored as glycogen and fat Fat kcal: 9 per gram Fat kcal: 9 per gram Glucose and fat preferred fuel (amino acids not stored) Glucose and fat preferred fuel (amino acids not stored) Glucose-major fuel Glucose-major fuel Metabolism under hormonal control Metabolism under hormonal control

Homeostatic Mechanisms (1) When glucose levels rise above a set point, (2) pancreas secretes insulin into the blood. (3) Insulin enhances the transport of glucose into body cells and stimulates the liver and muscle cells to store glucose as glycogen, dropping blood glucose levels. (4) When glucose levels drop below a set point, (5) the pancreas secretes glucagon into the blood. (6) Glucagon promotes the breakdown of glycogen and the release of glucose into the blood, increasing the blood glucose levels. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

See page 851—help identify process

Caloric Imbalances Undernourishment: chronic caloric deficiency Undernourishment: chronic caloric deficiency Overnourishment (obesity): Overnourishment (obesity): excessive food intake excessive food intake Leptin-appetite supressing hormone Leptin-appetite supressing hormone Malnourishment: essential nutrient deficiency Malnourishment: essential nutrient deficiency

Leptin deficient rat on left

Supplying carbon skeletons Build proteins, carbohydrates, lipids Build proteins, carbohydrates, lipids

Essential Nutrients Materials that must be obtained in preassembled form. (Why???) Materials that must be obtained in preassembled form. (Why???) Malnourishment: essential nutrient deficiency Malnourishment: essential nutrient deficiency

Essential amino acids: Essential amino acids: 8 8 Protein deficiency-most common type of malnutrition Protein deficiency-most common type of malnutrition

Complete & incomplete proteinsComplete & incomplete proteins Complementary proteinsComplementary proteins Limiting amino acids.Limiting amino acids.

Special Adaptations Adelei penguins- Antartica Adelei penguins- Antartica Use muscle protein to build new feathers Use muscle protein to build new feathers

Essential fatty acids: unsaturated fatty acids unsaturated fatty acids linoleic and alpha-linolenic (Ω-3; Ω-6) linoleic and alpha-linolenic (Ω-3; Ω-6) phospholipids in cell membranes— esp. nervous tissue Omega-3 fatty acids have been found to be beneficial for the heart. Positive effects include anti-inflammatory and anti-blood clotting actions, lowering cholesterol and triglyceride levels, and reducing blood pressure

Vitamins: Vitamins: many are organic coenzymes (B-vits) many are organic coenzymes (B-vits) a) water soluble-excreted a) water soluble-excreted b) fat soluble-stored in adipose tissue—can be toxic in excess b) fat soluble-stored in adipose tissue—can be toxic in excess A,D,E,K A,D,E,K A) Vision-Retinol; skin A) Vision-Retinol; skin D) bone development—rickets—bowed legs D) bone development—rickets—bowed legs E) antioxidant E) antioxidant K) blood clotting K) blood clotting

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Minerals: inorganic cofactors Minerals: inorganic cofactors Calcium: bones, muscle contraction, nerve impulses Calcium: bones, muscle contraction, nerve impulses Iodine: goiter: naturally occurring in marine water Iodine: goiter: naturally occurring in marine water Iron: oxygen transport (hemoglobin) Iron: oxygen transport (hemoglobin)

Food types/feeding mechanisms Opportunistic Opportunistic Herbivore: eat autotrophs Herbivore: eat autotrophs Carnivore: eat other animals Carnivore: eat other animals Omnivore: both Omnivore: both Feeding Adaptations Feeding Adaptations Suspension-feeders: sift food from water (baleen whale) Suspension-feeders: sift food from water (baleen whale) Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) Substrate-feeders: live in or on their food (leaf miner) (earthworm: deposit-feeder) Fluid-feeders: suck fluids from a host (mosquito); hummingbirds Fluid-feeders: suck fluids from a host (mosquito); hummingbirds Bulk-feeders: eat large pieces of food (most animals) Bulk-feeders: eat large pieces of food (most animals)

Overview of food processing-4 stages 1-Ingestion: act of eating 1-Ingestion: act of eating 2- Digestion : process of food break down 2- Digestion : process of food break down enzymatic hydrolysis 3- Absorption : cells take up small molecules 4- Elimination : removal of undigested material 4- Elimination : removal of undigested material

A) intracellular: breakdown within cells (sponges); or within membrane (paramecium) B) extracellular: breakdown outside cells (most animals) alimentary canals (digestive tract)

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig Extracellular digestion Hydra Hydra 2 tissue layers 2 tissue layers Inner layer Inner layer Forms digestive Cavity Incomplete digestive Incomplete digestiveSystem (only 1 opening) (only 1 opening)

Mammalian digestion (complete- 2 openings) Peristalsis: rhythmic waves of contraction by smooth muscle Peristalsis: rhythmic waves of contraction by smooth muscle Sphincters: ring-like valves that regulate passage of material Sphincters: ring-like valves that regulate passage of material Accessory glands: salivary glands; pancreas; liver; gall bladder Accessory glands: salivary glands; pancreas; liver; gall bladder

Mammalian digestion: Ingestion & initial digestion Oral cavity Oral cavity Mechanical and chemical digestion Mechanical and chemical digestion Teeth-reduce size\increase surface area Teeth-reduce size\increase surface area salivary amylase salivary amylase bolus bolus Pharynx-juncture Pharynx-juncture epiglottis-cartilage flap, closes epiglottis-cartilage flap, closes off trachea when swallowing off trachea when swallowing Esophagus—food tube Esophagus—food tube

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig Stomach Bolus passes through Cardiac Sphincter- stomach Bolus passes through Cardiac Sphincter-enters stomach (occasional backflow—heartburn) (occasional backflow—heartburn) Preliminary digestion, stores food Preliminary digestion, stores food Mechanical (churning) and chemical digestion Mechanical (churning) and chemical digestion gastric juice secreted: gastric juice secreted: Contains HCl & pepsin Contains HCl & pepsin (pepsinogen activated to pepsin by (pepsinogen activated to pepsin by HCl)-- begins protein digestion HCl)-- begins protein digestion Positive feedback-increasingly more pepsin activation

Small Intestine: Digestion & Absorption: Digestion of carbohydrates, proteins, nucleic acids, fats Acid Chyme passes through Pyloric Sphincter into Small intestine (duodenum) Acid Chyme passes through Pyloric Sphincter into Small intestine (duodenum) bile : secreted into S.I. bile : secreted into S.I. Produced by liver Produced by liver Stored in Gall Bladder Stored in Gall Bladder Bile salts-emulsifiers ( no enzymes)—break up & coat fat Bile salts-emulsifiers ( no enzymes)—break up & coat fat Some proteases secreted by intestine Some proteases secreted by intestine Pancreas: secretes bicarbonate & enzymes Pancreas: secretes bicarbonate & enzymes Amylases (carbs); lipases (fats); nucleases Amylases (carbs); lipases (fats); nucleases some proteases secreted in inactive form and activated by a membrane-bound enteropeptidase some proteases secreted in inactive form and activated by a membrane-bound enteropeptidase

Activation of pancreatic peptidases within the intestine

3. Nutrient Absorption S.I. highly folded S.I. highly folded Villi (finger-like projections) & microvilli (appendages of villi) increase absorptive surface Villi (finger-like projections) & microvilli (appendages of villi) increase absorptive surface Small vessels in villi absorb: Small vessels in villi absorb: Lipids into the lacteals –to veins Lipids into the lacteals –to veins Other nutrients into Hepatic Portal Vessel to Liver Other nutrients into Hepatic Portal Vessel to Liver

In Lumen-Chylomicrons form: (complex of fat, cholesterol, & protein) In Lumen-Chylomicrons form: (complex of fat, cholesterol, & protein) Carried by lacteals; dump into veins returning to the heart Carried by lacteals; dump into veins returning to the heart Other nutrients—travel to liver via Hepatic portal vessel Other nutrients—travel to liver via Hepatic portal vessel

Large intestine (colon)- absorb water; concentrate residue Large intestine (colon)- absorb water; concentrate residue Bacterial symbionts- generate some vitamins—K, biotin Bacterial symbionts- generate some vitamins—K, biotin Cecum-small pouch Cecum-small pouch At tip is the Appendix At tip is the Appendix Feces Feces Rectum--storage Rectum--storage Anus--elimination Anus--elimination Large Intestine

Hormonal Regulation of Digestion Hormonal Regulation of Digestion Gastrin food---> stomach wall ---> gastric juice Gastrin food---> stomach wall ---> gastric juice Enterogastrones (duodenum) Enterogastrones (duodenum) 1. Secretin - 1. Secretin - acidic chyme---> secretin --> pancreas to release bicarbonate (neutralize chyme) acidic chyme---> secretin --> pancreas to release bicarbonate (neutralize chyme) 2. Cholecystokinin (CCK) 2. Cholecystokinin (CCK) amino/fatty acids---> pancreas to release enzymes and gall bladder to release bile amino/fatty acids---> pancreas to release enzymes and gall bladder to release bile

Evolutionary adaptations Dentition: an animal’s assortment of teeth Dentition: an animal’s assortment of teeth Digestive system length Digestive system length Herbivores-longer Herbivores-longer Symbiosis Symbiosis Ruminants Ruminants

Symbionts: koala-- enlarged cecum, symbiotic bacteria ferment finely shredded eucalyptus leaves.

Ruminants—4 stomach chambers—microbial action Well developed for vegetation: which include deer, cattle, and sheep.

(1) (1) Cow first chews and swallows a mouthful of grass (2) (2) boluses enter the rumen and (2) the reticulum. Symbiotic bacteria and protists digest this cellulose-rich meal, secreting fatty acids. Periodically, the cow regurgitates and rechews the cud, which further breaks down the cellulose fibers. (3) The cow then reswallows the cud, which moves to the omasum; water is removed. (4) The cud, with many microorganisms, passes to the abomasum for digestion by the cow’s enzymes. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

The length of the vertebrate digestive system is also correlated with diet. In general, herbivores and omnivores have longer alimentary canals relative to their body sizes than to carnivores, providing more time for digestion and more surface area for absorption of nutrients. Vegetation is more difficult to digest than meat because it contains cells walls. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

(1) Heterotrophic protists engulf their food by phagocytosis or pinocytosis and (2) digest their meals in food vacuoles. (3) Newly formed vacuoles are carried around the cell (4) until they fuse with lysosomes, which are organelles containing hydrolytic enzymes. (5) Later, the vacuole fuses with an anal pore and its contents are eliminated. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig

Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings Fig